Undefined if constexpr?

Asked Apr 25 '15 at 21:06

Active Apr 25 '15 at 21:17

Viewed 54 times

This little piece of code drives me a bit crazy:

struct my_struct
{
private:
    static constexpr const char* some_string() noexcept;
public:
    my_struct() = default;
private:
    std::string _my_string{some_string()};
}

//in cpp
constexpr const char* my_struct::some_string() noexcept
{
    return "Lorem ipsum dolor sit amet, consetetur sadipscing elitr,"
           "sed diam nonumy eirmod tempor invidunt ut labore et"
           " dolore magna aliquyam erat, sed diam voluptua.";
}

My compiler, g++ (Debian 4.9.2-10) 4.9.2, is complaining that some_string is undefined! Removing the constexpr-keyword solved the problem, but still whats the reason for this?

Is it some C++ rule I simply have missed or is it a compiler bug or neither of those options?

edited Apr 25 '15 at 21:17

asked Apr 25 '15 at 21:06

NaCl

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1

The definition is in the C++ file, right? – Sergey Kalinichenko Apr 25 '15 at 21:10
@dasblinkenlight Yes. – NaCl Apr 25 '15 at 21:10
It's a duplicate then :-) – Sergey Kalinichenko Apr 25 '15 at 21:11
1

missing `;` perhaps after the `struct` declaration? I can compile your code with no problems on gcc4.9.2 macports. http://ideone.com/qGbWXY – vsoftco Apr 25 '15 at 21:11
@dasblinkenlight How so? the class only provides a declaration, or so it seems to me – The Vivandiere Apr 25 '15 at 21:12
2

@Golazo This works for all functions except `constexpr`. Their definitions must be in the header in order to be useable in other translation units. – Sergey Kalinichenko Apr 25 '15 at 21:14

Undefined if constexpr?

0 Answers0